even though I'm new to Salehoo, I can tell you that over the last year, I've been selling antivirus softwares keys on eBay. No physical stuff to ship through the post office, only emails. It's easy and it gets me around 10$ each key. Be careful though as the company may have pretty strict rules. But if you have a bit of time to spend emailing the company and asking for permissions, you can make a fair amount of $
Hope that helps!
BTW this post is a very nice idea!